Essential elements of a generic center rotor type milling machine are a machine part having a machine frame, an operator platform, a drive engine as well as travelling devices driven by the drive engine, such as wheels and/or crawler tracks. Preferably, all travelling devices are connected to the machine frame via height-adjustable lifting columns so that the distance of the machine frame to the ground in the vertical direction can be adjusted by adjusting the lifting columns. Furthermore, a generic center rotor type milling machine comprises a milling unit having a milling drum for milling ground material and a milling drum box for covering the milling drum to the sides and upward. The milling unit can be detachably fastened to the machine frame in the working direction between the front and the rear travelling devices via a fastening device fastening the milling drum box to the center rotor type milling machine. Such a center rotor type milling machine is known from DE 10 2011 018 222 A1, for example. The invention described therein particularly relates to road milling machines.
Generic center rotor type milling machines are usually used in road and pathway construction. Center rotor type milling machines of the road cold milling machine type are used for milling off a road surface layer for road renewal. Generic center rotor type milling machines are generally also referred to as large-scale milling machines. In these machines, the milling unit is, in a spaced manner, situated in the working direction between the front and the rear travelling devices, normally wheels or crawler tracks, said front or rear travelling devices comprising either a pair of devices or a single device. An essential aspect for the application range of such a center rotor type milling machine is the width of the milling drum arranged on said center rotor type milling machine, the milling drum usually being a hollow-cylindrical unit with a plurality of milling tools being arranged in a known manner on the outer jacket surface of said unit. The milling drum is usually supplied with drive energy by the drive unit of the center rotor type milling machine, for example, via a mechanic or hydraulic drive train. The milling drum rotates inside a milling drum box about a horizontal rotation axis extending transversely to the working direction and mills off ground material when in a state immersed in the ground. Here, the milling drum box relates to a housing-like entirety with the milling drum being arranged therein and protruding toward the ground. The milling drum box prevents milled material from being thrown around in an uncontrolled manner during working operation and additionally provides a compartment for controlled guidance of milled material. In other words, the milling drum box, while being open toward the ground, surrounds the milling drum partially in the horizontal direction and in the vertical direction upwards. It is known to design the milling unit as a demountable entirety, comprising the milling drum and the milling drum box, at the machine part of the center rotor type milling machine. For example, demounting the milling unit may be desired when the center rotor type milling machine is to be lightened, for example, for transport purposes. Working times required for dismounting and mounting the milling unit from/to the machine part are, of course, desired to be as short as possible. Furthermore, there is often a need for being able to mill various milling widths with one and the same center rotor type milling machine. To that end, it is preferred if various milling units can be mounted and quickly exchanged amongst one another on one and the same center rotor type milling machine. In particular, this relates to the use of so-called large-scale milling machines having a milling unit arranged between the front and rear travelling devices. The option of dismounting the milling unit as an entirety from the machine part is described in DE 10 2011 018 222 A1, for example. To that end, the milling drum box is connected to the machine part in a detachable manner via massive fastening screws and corresponding lock nuts. The disadvantage of said configuration lies with the fact that the fastening screws are oftentimes hardly accessible, which is why other parts of the center rotor type milling machine need to be removed first in order to allow access to the fastening screws. Moreover, said screws are comparatively large screws, so that a great force must be applied for mounting and dismounting. This is a challenge particularly in constricted space. Furthermore, in this alternative, time expenditure for the mounting and dismounting or changing of the milling unit is comparatively high as well. When referring to the dismounting and mounting of the milling unit hereinafter, this is to be understood as equally comprising mounting and dismounting one and the same milling unit as well as changing the milling unit, i.e., dismounting a first milling unit and mounting a second milling unit.